US 8,015,156 B2Granted

Systems and methods for a snapshot of data

AssigneeEMC Corporation

InventorsRobert J. Anderson, Neal T. Fachan, Justin M. Husted, Eric M. Lemar, Aaron J. Passey, Darren P. Schack

Life of this patent

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Abstract

In one embodiment, a user or client device is connected to a distributed file system comprised of one or more physical nodes. The data on each of the physical nodes store metadata about files and directories within the file system. Some of the embodiments permit a user to take a snapshot of data stored on the file system. The snapshot may include a single file, a single directory, a plurality of files within a directory, a plurality of directories, a path on the file system that includes nested files and subdirectories, or more than one path on the file system that each includes nested files and directories. According to one embodiment, the system stores representations of the snapshots that govern a file or directory and its descendants within metadata associated with that file or directory. In one embodiment, before modifying a file or directory, the system updates the representations of the governing snapshots by traversing the metadata of ancestors of the file or directory.

Claims18

Dependent claims

A system for preserving access to previous versions of directories and files stored in a processor-accessible storage system, the system comprising:

at least one memory;
at least one computer processor;
a plurality of metadata structures logically arranged in a hierarchical structure and stored on the at least one memory, each metadata structure corresponding to a file or directory of a file system and comprising a governance list configured to store two or more snapshot identifiers, each snapshot identifier identifying a snapshot governing at least the corresponding file or directory, wherein the plurality of metadata structures comprises:
a target metadata structure that corresponds to a target file or directory of the file system;
and
a parent directory metadata structure that corresponds to a parent directory of the file system that is a logical parent of the target file or directory;
and
at least one executable software module executed by the at least one computer processor and configured to:
access a governance list of the parent directory metadata structure, wherein the governance list of the parent directory metadata structure is configured to store two or more snapshot identifiers, and wherein each snapshot identifier identifies a snapshot governing at least the parent directory;
identify a snapshot governing the parent directory that also governs the target file or directory and is not reflected in the governance list of the target metadata structure based on the accessed governance list of the parent directory metadata structure;
and
add a snapshot identifier corresponding to the identified snapshot to a governance list of the target metadata structure.

9 more elements

A method of preserving access to previous versions of directories and files stored in a processor-accessible storage system, the method comprising:

obtaining, by a computer processor, a plurality of metadata structures stored on at least one memory, each metadata structure corresponding to a file or directory of a file system and comprising a governance list configured to store two or more snapshot identifiers, each snapshot identifier identifying a snapshot governing at least the corresponding file or directory;
accessing, by the computer processor, a governance list of a parent directory metadata structure, wherein the parent directory metadata structure corresponds to a parent directory of the file system that is a logical parent of a target file or directory of the file system, wherein the governance list of the parent directory metadata structure is configured to store two or more snapshot identifiers, and wherein each snapshot identifier identifies a snapshot governing at least the parent directory at;
identifying, by the computer processor, a snapshot governing the parent directory that also governs the target file or directory and is not reflected in the governance list of the target metadata structure based on the accessed governance list of the parent directory metadata structure;
and
adding, by the computer processor, a snapshot identifier corresponding to the identified snapshot to a governance list of a target metadata structure corresponding to the target file or directory.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/717,869Filed 4 Mar 2010 · continuation
Priority: 18 Aug 2006
Published: US 2010/0161557 A124 Jun 2010
Granted: 6 Sep 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G06F 16/174
Details of further file system functions: redundancy elimination performed by the file system
G06F 16/128
File system administration, e.g. details of archiving or snapshots: details of file system snapshots on the file-level, e.g. snapshot creation,…
Y10S 707/99953
Coherency, e.g. same view to multiple users: recoverability
G06F
Computing and data processing

Family

Application11/506,610Parent of this continuation · filed 18 Aug 2006
US 7,680,836 B2Parent of this continuation · filed 16 Mar 2010
US 2010/0161557 A1Pre-grant publication · published 24 Jun 2010
US 2008/0046476 A1Published application
US 8,015,156 B2This patent

From the US filing history. Foreign family members aren’t listed.